#box{
    width: 300px;
    border: 1px solid #000;
}

#btn{
    padding: 0;
    margin: 0;
}

#btn li{
    list-style: none;
    width: 100px;
    height: 30px;
    float: left;
    border-bottom: 1px solid #000;
    background-color: #000;
    line-height: 30px;
    text-align: center;
    color: #fff;
}
#btn .actived{
    background-color: #ccc;
    color: #000;
}
#tab{
    margin-top: 40px;
}
#tab li{
    display: none;
}

#tab li span{
    display: block;
    width: 200px;
    height: 30px;
    float: left;
    font-size: 14px;
    line-height: 30px;
}

.clear{
    clear: both;
}